Implement IDBVersionChangeEvent ctor w/ IDBVersionChangeEventInit dict

Source/bindings/v8/Nullable.h

+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef Nullable_h
+#define Nullable_h
+
+#include "wtf/Assertions.h"
+
+namespace WebCore {
+
+template <typename T>
+class Nullable {
+public:
+    Nullable()
+        : m_value()
+        , m_isNull(true) { }
+
+    Nullable(const T& value)
+        : m_value(value)
+        , m_isNull(false) { }
+
+    Nullable(const Nullable& other)
+        : m_value(other.m_value)
+        , m_isNull(other.m_isNull) { }
+
+    Nullable& operator=(const Nullable& other)
+    {
+        m_value = other.m_value;
+        m_isNull = other.m_isNull;
+        return *this;
+    }
+
+    T get() const { ASSERT(!m_isNull); return m_value; }
+    bool isNull() const { return m_isNull; }
+
+    operator bool() const { return !m_isNull && m_value; }
+
+    bool operator==(const Nullable& other) const
+    {
+        return (m_isNull && other.m_isNull) || (!m_isNull && !other.m_isNull && m_value == other.m_value);
+    }
+
+private:
+    T m_value;
+    bool m_isNull;
+};
+
+} // namespace WebCore
+
+#endif // Nullable_h